>>212838301MoS wasn't a commercial failure, it was considered a slight underperformance since they expected more due to the climate of Capeshit at the time. It still very much made a profit.
The problem with Man of Steel was that it received very mixed reviews, and had an extremely brutal second weekend box office drop due to poor word of mouth. These are not the type of indicators you want when starting a franchise. But even then it did well enough for a sequel, which is what really doomed the franchise because one BvS got even worse reviews, and had a worse dropoff, WB panicked.